Bearing Installation and Maintenance

The service life of rolling mill bearings is not only related to the quality of bearings, but also closely related to whether they are correctly installed and maintained. Therefore, it is necessary to attach importance to the technical requirements for the installation and maintenance of rolling mill bearings and to formulate this operation regulation.

I. Installation of Rolling Mill Bearings

1. Before installation, the mating surfaces of various mating parts (rolls, bearing seats, pressure caps, locking parts, etc.) related to bearing installation should be carefully inspected to check whether their dimensions and shape tolerances meet the design requirements; and the requirements for cleanliness, no burrs and protruding heights should be required; the parts that do not meet the requirements are not allowed to be installed.

2. Unseal the oil seal package of the bearing before installing the bearing, and clean the rust-proof oil of the bearing. After checking and checking of bearings, sufficient lubricating grease should be applied on all rolling surfaces of bearings. When applying the grease, certain pressure should be applied and the rollers should be rotated. The grease should be added to the raceway surface of the outer ring of bearings.

3. Heating bearing inner rings with bearing heater or hot oil, whose temperature is controlled at 90-100 C, and no more than 120 C. After heating the inner rings, wipe off the oil stain on the surface with a rag. The inner rings should be quickly loaded into the roll neck and applied with axial pressure to ensure that the assembly is in place at one time, and there is no clearance between the inner rings and the shoulder position. The inner ring is not allowed to be magnetic.

4. When installing the outer components of bearings, first install the inner pressure cap on the side of the roller body on the bearing seat, then put the end face down vertically and safely into the bearing. When installing, the bearing should be loaded evenly, and should not be hit directly by hammer. When operating, if the outer components are stuck, the outer rings can be loaded at the chamfer with copper hammer or copper rod, or with the help of the installation ring, but do not drop dirty materials such as copper scraps into the bearing.

5. Before installing matching bearings, grease should also be applied before assembly.

6. After installing the inner bearing of the bearing seat, apply the grease again and remove the excess grease. The grease filling amount is 1/2-2/3 of the inner part of the bearing, and the outer part and sealing part of the bearing should be filled as much as possible.

7. The bearing outer ring assembly should be marked and recorded when it is installed, so as to change the position of outer ring load area regularly. Bearing outer ring assembly is used interchangeably in pairs, and can not be used in pairs.

8. No clearance is allowed between the components installed in the bearing and the contact surface positioned by the bearing, but the outer cover of the outer bearing should not be pressed to death first, so as to facilitate the alignment of the supporting bearing when loading the roll.

9. Place the roll in the horizontal position on the assembly support, apply appropriate amount of grease, and hoist the assembled bearing seat horizontally with appropriate hoisting tools. Careful attention should be paid to the concentricity between the bearing seat and the roll, and then push the bearing seat slowly into the roll. Care should be taken not to touch the rollers and raceways during assembly.

10. All fasteners can be tightened after the parts are installed correctly.

11. Turn the bearing seat at last to make sure that the bearing seat rotates flexibly on the roll without obstruction. If it is not flexible, it should be removed to check the cause of its failure.

Ⅱ. Removal of rolling mill bearings

1. The disassembly sequence is contrary to the installation sequence. When disassembling, we must pay attention to the concentric hoisting of the bearing seat and the roll horizontally, and do not scratch the rollers and raceways.

2. Use hydraulic disassembly tools or special disassembly tools for disassembly. It is not allowed to disassemble bearings by directly hitting the edges, rollers and cages.

3. Do not mix the removed bearing components, and remember the bearing load position, so as to change the load position when reassembling.

Ⅲ. Inspection and Maintenance of Rolling Mill Bearings

Because the rolling mill is operated under heavy load, in order to reduce the bearing damage caused by fatigue or lubrication failure of bearing materials, improve the service life of bearings and reduce the phenomenon of burning bearings in rolling line, periodic inspection and maintenance of bearings are necessary.

1. Every time the mill grinds and changes the rolls, it is necessary to carefully check the use of bearings in the bearing seat, whether the rotation is normal, whether there are abnormal phenomena such as pitting and peeling, grease pollution and failure, if there are problems, it is necessary to carry out further cleaning inspection.

2. Bearings are regularly cleaned, checked and maintained to change the load position. The time of maintaining and changing the load position should be formulated according to the statistical law of service life of rolling mill bearings, that is, when the average fatigue life time of rolling mill bearings is 1/2-2/3.

3. After the bearings are disassembled, they should be carefully cleaned and used grease and oxide scales should be cleaned.

4. Visual inspection of bearings with or without bumps, cracks, cage deformation, rust, pitting, spalling and other phenomena, to rotate the rolling body for inspection.

5. The surface of roller and raceway is slightly rusted and pitted. It can be used for repairing the worn surface with oil stone, but it must be installed in the non-load area.

6. Check the reliability of seals when changing rollers every time, and replace seals in time if aging occurs.

7. Monitoring and maintenance in rolling process:

(1) Normal rolling process and correct mill installation adjustment.

(2) Let the cooling water flow directly to the seal as little as possible to reduce the water and oxide skin entering the bearing interior.

(3) Implement noise monitoring: Normal operation should be a steady buzz, regular detection and comparison of normal sound, timely detection of abnormal situation and timely treatment.

(4) Implement temperature monitoring: periodically observe the temperature, the temperature is gradually rising, when the operation will be abnormal, if there are abnormalities, we should deal with them in time to avoid burning the rolls.

8. Bearings should be protected against rust and dust. Paper oil seals should be used when bearings and bearing seats are not installed for the time being.

9. Carefully do a good job of bearing use record card, in order to master the amount of steel passing and maintenance testing.